Whenever I disassemble my Holley, I notice that the vacuum side of the power valve metering block gasket is wet. Is this normal? If it isn't new gasket or double up on them? They are the blue silicone reusable ones.

In regards to the fuel seen on that side, if your using a power valve plug many times they act as being too deep and bottom out on the center section of the Carb body and cocking the metering plate.
Look for signs of contact by the plug on the center section and correct for the excess thickness of the Carb body with a 3 second grinding session!

That is probably just from the gasoline vapor that is in the intake when the engine is running. After all that cavity behind the power valve is connected directly to the intake. It doesn't necessarily mean that there is anything wrong with the carburetor.

That is probably just from the gasoline vapor that is in the intake when the engine is running. After all that cavity behind the power valve is connected directly to the intake. It doesn't necessarily mean that there is anything wrong with the carburetor.

How would vapor get in there if there's nothing sucking it up into that space, especially through a tiny hole, and it leaves a Horizontal wet line???

In regards to the fuel seen on that side, if your using a power valve plug many times they act as being too deep and bottom out on the center section of the Carb body and cocking the metering plate.
Look for signs of contact by the plug on the center section and correct for the excess thickness of the Carb body with a 3 second grinding session!

No plug ,but I do use a plastic p/v gasket. Would that do it? I do get 15"HG at idle.

That is probably just from the gasoline vapor that is in the intake when the engine is running. After all that cavity behind the power valve is connected directly to the intake. It doesn't necessarily mean that there is anything wrong with the carburetor.

How would vapor get in there if there's nothing sucking it up into that space, especially through a tiny hole, and it leaves a Horizontal wet line???

When the engine is running and you open and close the throttle the pressure in the intake manifold as well as the pressure in that chamber behind the power valve changes. That's how liquid fuel can be drawn into that area. How would it leave a liquid line if the vacuum hole to the intake was actually open would be a better question.

That is probably just from the gasoline vapor that is in the intake when the engine is running. After all that cavity behind the power valve is connected directly to the intake. It doesn't necessarily mean that there is anything wrong with the carburetor.

How would vapor get in there if there's nothing sucking it up into that space, especially through a tiny hole, and it leaves a Horizontal wet line???

When the engine is running and you open and close the throttle the pressure in the intake manifold as well as the pressure in that chamber behind the power valve changes. That's how liquid fuel can be drawn into that area. How would it leave a liquid line if the vacuum hole to the intake was actually open would be a better question.

I also have the p/v blowout obstruction there also,so less chance of it getting in there.